Hi zzl112100! To post a project on the forums all you have to do is create an attachment and upload the .a2w file from your computer! That's it!
Plus if your Alice file is too big, then I find that MediaFire or DropBox are good choices, because then if it exceeds the 20mb maximum, I think those storage providers will allow it. Then all you have to do is paste the download link and you're good to go!
A fun thing that I recommend a beginner or anyone can do is an official Alice.org activity at,
http://www.alice.org/HourOfCode/introduction.html there's a step by step scene set up activity! You could even play one of the Alice example worlds such as Flight Simulator and edit it to make it even better!
Connor + Alice Forever! (-:
Website: www.mccgameco.com
Have a nice day!
Also, I've been gone for a really long time, more than I can even remember and am now going to be way more active! :-D